When implant materials are used and are subjected to a substantial mechanical load, a high strength is the primary requirement. This is achieved by using essentially conventional construction materials--e.g. stainless steel, cobalt-chromium alloys, titanium and titanium-alloys, various ceramic materials such as silicon nitride and polymers. In order to fix implants, it is common practice to utilize a topographical surface or pores. In this connection special requirements as to holding and bone ingrowth must be met. A prior Swedish patent application No. 9101677-4 includes some important new aspects regarding primarily the pore size distribution. Thus, specific and complex pore size distributions can be utilized to accommodate bone ingrowth-promoting agents and to provide a satisfactory bone ingrowth in large pores.